Pronunciation: (un"dur-pin'), [key]
—v.t., -pinned, -pin•ning.
1. to prop up or support from below; strengthen, as by reinforcing a foundation.
2. to replace or strengthen the foundation of (a building or the like).
3. to furnish a foundation for; corroborate: The author's conclusions are underpinned by references to experimental findings.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.